A thunderstorm over Wahiawa last night (Thursday, April 10) caused a flicker in Hawaiian Electric Company power lines, tripping off an ultra-violet disinfection system at the Wahiawa Wastewater Treatment Plant.The power interruption resulted in the discharge into Lake Wilson of about 14,000 gallons of effluent that had undergone tertiary treatment, but not the final ultraviolet (UV) disinfection.

The incident occurred from 5:51 p.m. to 6:01 p.m.The UV disinfection units re-set themselves and resumed their normal functions once power was restored.

Warning signs are being posted in affected areas and the State Department of Health has been notified.State and city workers involved in salvinia removal at Lake Wilson have also been informed of the incident.